Acalculous cholecystitis is inflammation of the gallbladder that develops without gallstones. It accounts for a meaningful slice of all gallbladder inflammation cases, and it tends to behave differently from its stone-related counterpart in ways that matter for diagnosis, treatment, and survival. The condition is most closely associated with critically ill patients in intensive care, but it can also appear in otherwise healthy people, in children with viral infections, and in patients with autoimmune disease.
What Makes It Different from Gallstone Cholecystitis
Most gallbladder inflammation starts when a stone blocks the cystic duct. Bile backs up, the gallbladder wall stretches and swells, and infection may follow. In acalculous cholecystitis, none of that happens. There is no stone. Instead, the gallbladder becomes inflamed through mechanisms that are fundamentally systemic rather than local. Tissue studies have borne this out: when researchers compared gallbladder specimens from patients with acalculous disease to those with stone-related inflammation, the acalculous group showed more bile infiltration extending deep into the muscle layer, while the stone group showed more epithelial damage and localized necrosis typical of a blocked, overstretched organ.1PubMed. Histopathology of acute acalculous cholecystitis in critically ill patients The researchers concluded that acalculous cholecystitis is largely a manifestation of whole-body critical illness, while stone cholecystitis is a local gallbladder problem.
This distinction matters practically. A seven-year study at a single center found that acalculous cholecystitis patients were older on average, more often male, and more likely to have diabetes. The mortality rate was dramatically higher: roughly 19% for the acalculous group compared to about 4% for stone-related cholecystitis, with more perforations and longer hospital stays.2PubMed Central. The Microbiological Spectrum and Antibiotic Resistance in Acute Acalculous and Calculous Cholecystitis: A Seven-Year Study in a Tertiary Center Those numbers reflect the fact that acalculous cholecystitis tends to strike people who are already seriously unwell.
How a Gallbladder Gets Inflamed Without Stones
Two overlapping mechanisms drive most cases. The first is ischemia, meaning reduced blood flow to the gallbladder wall. The gallbladder is supplied by a single artery, the cystic artery, with limited collateral circulation. When blood pressure drops, when sepsis triggers widespread vasodilation, or when vasopressor drugs constrict the splanchnic circulation, the gallbladder can become starved for oxygen. Endothelial damage follows, along with microvascular clotting within the gallbladder wall itself.3PubMed Central. Gallbladder perforation in acute acalculous vs. calculous cholecystitis: a retrospective comparative cohort study with 10-year single-center experience
The second mechanism is bile stasis. When a patient has not eaten for an extended period, the gallbladder never receives the hormonal signal to contract and empty. Bile concentrates and sits, irritating the mucosa and creating a hospitable environment for bacteria. Long-term total parenteral nutrition (intravenous feeding) is one of the best-documented triggers for this stasis. Researchers showed that daily injections of cholecystokinin, the hormone that normally makes the gallbladder squeeze, could prevent the stasis caused by parenteral nutrition.4PubMed Central. Cholecystokinin prophylaxis of parenteral nutrition-induced gallbladder disease
In real patients, both mechanisms usually operate at once. A person in the ICU on mechanical ventilation, receiving vasopressors and not eating, is experiencing ischemia and bile stasis simultaneously. A case series examining patients with sepsis and low blood pressure found that arterial hypoperfusion of the gut appeared central to the development of acalculous cholecystitis, with bacterial invasion of the gallbladder following the initial ischemic injury and frequently progressing to gangrene.5PubMed. Acute acalculous cholecystitis associated with systemic sepsis and visceral arterial hypoperfusion: a case series and review of pathophysiology Positive-pressure ventilation and opioid therapy, both common in critical care, have also been implicated because they further reduce gallbladder motility and splanchnic blood flow.
Who Gets It
The classic patient is someone in the ICU after major surgery, severe trauma, or multiorgan illness. But the condition shows up across a surprisingly wide range of clinical situations.
Burn patients are a well-studied group. A study of over 1,200 significant burns found acalculous cholecystitis in about 1.2% of admissions. That sounds low until you consider that this subgroup had a mortality rate above 50%. In multivariate analysis, the strongest independent predictors were older age, the volume of blood transfusions received, and the duration of mechanical ventilation.6PubMed. Acalculous cholecystitis in severely burned patients: incidence and predisposing factors A separate case report described acalculous cholecystitis appearing about 45 days after high-voltage electrical burns in a patient who had already required amputation of both upper limbs, underscoring that this complication tends to arise weeks into a prolonged critical illness.7PubMed Central. Acute acalculous cholecystitis – a rare complication of burn injury
Cardiac surgery patients face a particular vulnerability. Cardiopulmonary bypass can temporarily reduce blood flow to the gut, and one review of gastrointestinal complications after cardiac surgery found that acalculous cholecystitis was the most lethal of all GI complications, with a mortality rate of 86% in that series.8PubMed. Gastrointestinal complications after cardiac surgery That number is from an older study and likely reflects delayed diagnosis in an era when the condition was less well recognized, but it highlights why clinicians remain watchful for abdominal symptoms after heart operations.9PubMed. Acute acalculous cholecystitis after cardiovascular surgery
Viral and Other Infectious Triggers
Not all acalculous cholecystitis is born in the ICU. A growing body of literature links it to infections, particularly viral ones, in patients who were previously healthy. Epstein-Barr virus, the agent behind infectious mononucleosis, is one of the most frequently reported triggers. Cases have been documented in teenagers and adults presenting with typical mono symptoms who then develop right-upper-quadrant pain.10PubMed Central. Acute Acalculous Cholecystitis by Epstein-Barr Virus Infection: A Rare Association Researchers have suggested that this association is more common than previously suspected, and that many cases go undiagnosed because the gallbladder inflammation is relatively mild and laboratory values may not show the dramatic abnormalities clinicians expect.11PubMed. Epstein-Barr virus infection with acute acalculous cholecystitis in previously healthy children
Hepatitis A is another documented trigger. The proposed mechanism involves direct viral invasion of gallbladder epithelial cells, since viral antigen has been detected in the gallbladder lining of affected patients.12PubMed Central. Epstein-Barr virus – associated acute acalculous cholecystitis in an adult Other infectious causes that have been linked to acalculous cholecystitis include Salmonella, cytomegalovirus, and various parasitic infections. In areas where these infections are more prevalent, they should stay on the diagnostic radar when a patient without gallstones develops gallbladder inflammation.13PubMed Central. Acute acalculous cholecystitis due to infectious causes
A Different Disease in Children
In adults, acalculous cholecystitis represents a minority of cholecystitis cases. In children, the picture is reversed. Acalculous disease is estimated to account for 50% to 70% of all childhood cholecystitis.14PubMed Central. Acute acalculous cholecystitis in children That reversal makes sense when you consider that gallstones are uncommon in young children, while viral illnesses are not.
A retrospective study of 147 pediatric cases found the average age was about five years, with roughly equal numbers of boys and girls. The most common underlying trigger was infectious disease, present in 70% of cases. Systemic diseases and malignancy accounted for smaller fractions. The most frequent clinical signs were elevated inflammatory markers, liver enlargement, and loss of appetite.15PubMed. Risk factors for poor outcomes of children with acute acalculous cholecystitis Another series of 13 children described fever, right-upper-quadrant pain, and vomiting as the typical triad, with jaundice in about a third and an abdominal mass palpable in roughly a quarter. Most had elevated white blood cell counts and abnormal liver tests.16PubMed. Acalculous cholecystitis in children
The good news is that infection-related acalculous cholecystitis in children often resolves with supportive care and does not always require surgery, particularly when it accompanies a self-limited viral illness. The condition is still taken seriously, though, because delayed recognition can lead to the same complications seen in adults.
When Autoimmune Disease Is the Culprit
A less commonly recognized cause is vasculitis, a family of conditions in which the immune system attacks blood vessel walls. When medium-sized arteries supplying the gallbladder are involved, the result can be ischemic gallbladder inflammation without a stone in sight. Polyarteritis nodosa is the vasculitis most frequently reported in this context, and it can cause gangrenous acalculous cholecystitis through arteritis of the gallbladder wall.17PubMed. Gastrointestinal involvement in polyarteritis nodosa In one case, the diagnosis of polyarteritis nodosa was only made after the gallbladder was removed and histology revealed necrotizing vasculitis in the specimen.18PubMed Central. Polyarteritis nodosa presenting as cholecystitis—a case report
An analysis of 61 patients with gallbladder vasculitis mapped out the range of systemic vasculitides that can affect the organ, including hepatitis B-associated vasculitis, cryoglobulinemic vasculitis, microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis. Acalculous cholecystitis was more common in the systemic vasculitis group than in those with vasculitis confined to the gallbladder alone.19PubMed Central. Single-organ gallbladder vasculitis: characterization and distinction from systemic vasculitis involving the gallbladder. An analysis of 61 patients. For clinicians, this means that acalculous cholecystitis in a patient with unexplained systemic symptoms, rashes, or kidney problems should prompt consideration of an underlying vasculitis.
How It Is Diagnosed
Diagnosing acalculous cholecystitis can be tricky because the patients most prone to it are often sedated, intubated, or otherwise unable to describe their symptoms clearly. In practice, bedside ultrasound is the first-line tool. A comparison of imaging modalities found that ultrasound was highly sensitive (92%) and highly specific (96%) for the diagnosis. CT scanning performed even better in the same study, reaching 100% on both measures, but ultrasound has the advantage of being portable, inexpensive, and immediately available at the bedside of a critically ill patient.20PubMed. The diagnosis of acute acalculous cholecystitis: a comparison of sonography, scintigraphy, and CT
Key ultrasound findings include a distended gallbladder, thickening of the gallbladder wall (typically above four millimeters), sludge within the gallbladder lumen, and fluid surrounding the organ. None of these findings alone is definitive, especially in ICU patients who may have gallbladder wall thickening for other reasons such as fluid overload or low albumin. The clinical picture has to match. Hepatobiliary scintigraphy (the HIDA scan) was notably less useful in the same comparative study, with a specificity of only 38% due to frequent false-positive results in critically ill patients who had impaired gallbladder filling for reasons unrelated to cholecystitis.
Why Speed Matters
Acalculous cholecystitis progresses faster and more aggressively than stone-related disease. Roughly half of patients develop severe gallbladder complications including gangrene, empyema (a gallbladder filled with pus), or perforation.21PubMed Central. Gallbladder perforation in acute acalculous vs. calculous cholecystitis: a retrospective comparative cohort study with 10-year single-center experience A study of 52 patients with acalculous cholecystitis found severe complications present in 27 of them. Older age and a higher white blood cell count were significant predictors of these severe outcomes.22PubMed Central. Clinical predictors of severe gallbladder complications in acute acalculous cholecystitis The ischemic mechanism behind the disease means that the gallbladder wall can die and perforate much faster than in a stone-obstructed but normally perfused gallbladder.
Treatment Options
Treating acalculous cholecystitis requires balancing the urgency of the gallbladder problem against the reality that many of these patients are too sick for major surgery. Historically, open cholecystectomy (surgical removal of the gallbladder) was the standard approach, but percutaneous cholecystostomy, a procedure in which a drainage tube is placed through the skin directly into the gallbladder under imaging guidance, has become the frontline intervention for the sickest patients.
Percutaneous cholecystostomy has a technical success rate of 95% to 100% and a very low complication rate.23PubMed Central. Percutaneous Cholecystostomy: Evidence-Based Current Clinical Practice A systematic review described it as an important treatment with an excellent safety profile, used successfully both as a standalone definitive procedure and as a temporary bridge until a patient is stable enough for surgery.24PubMed Central. Percutaneous cholecystostomy… why, when, what next? A systematic review of past decade A recent consensus panel agreed that percutaneous drainage is preferred over laparoscopic cholecystectomy specifically for the management of acute acalculous cholecystitis, with 80% agreement among the panelists. The same panel recommended it as a definitive treatment in patients with severe comorbidities who are poor surgical candidates.25JAMA Network Open. Management of Percutaneous Cholecystostomy Drains: A Consensus Statement
When surgery is performed, laparoscopic cholecystectomy is strongly preferred over the open approach. A large multicenter study comparing the two found that laparoscopic surgery was associated with lower mortality, lower complication rates, less frequent ICU admission, shorter hospital stays, and lower costs. About a quarter of laparoscopic cases did need to be converted to open surgery, which is a higher conversion rate than for elective gallbladder removal and reflects the inflamed, friable tissue surgeons encounter in acalculous disease.26PubMed. Emergent cholecystostomy is superior to open cholecystectomy in extremely ill patients with acalculous cholecystitis: a large multicenter outcome study
Endoscopic Alternatives
Newer techniques offer drainage routes that avoid both skin puncture and major surgery. Endoscopic ultrasound-guided gallbladder drainage is performed by passing an endoscope into the stomach or duodenum and creating a direct fistula into the gallbladder under ultrasound guidance, through which a stent is placed. A meta-analysis comparing three drainage approaches found that this endoscopic ultrasound-guided method achieved a clinical success rate of about 97%, which was significantly higher than either the transpapillary endoscopic route (about 88% clinical success) or percutaneous drainage (about 89% clinical success). Percutaneous drainage still had the highest technical success rate at nearly 99%, while the endoscopic ultrasound-guided approach achieved about 95%.27PubMed Central. Endoscopic ultrasound-guided gallbladder drainage, transpapillary drainage, or percutaneous drainage in high risk acute cholecystitis patients: a systematic review and comparative meta-analysis These endoscopic methods are gaining traction in specialized centers, though availability remains limited compared to percutaneous drainage.
Community-Acquired Cases
It is worth noting that acalculous cholecystitis does not exclusively belong to the ICU. A retrospective study of 20 outpatients who presented to an emergency department with acalculous cholecystitis found that cardiovascular risk factors dominated the clinical picture: hypertension, ischemic heart disease, diabetes, and high cholesterol were the most common comorbidities. Half of patients showed elevations in at least two of three standard inflammatory markers, though a fifth had no laboratory abnormalities at all. No deaths occurred in this cohort within 30 days, though about a third of the gallbladder specimens showed necrotic changes at the time of surgery.28International Journal of Clinical Case Reports and Reviews. Clinical Presentation and Risk Factors of Acalculous Cholecystitis in Outpatients: Retrospective Study The cardiovascular profile of these outpatients fits the ischemic theory of the disease: people with widespread vascular disease are plausibly at higher baseline risk of reduced gallbladder perfusion even without an acute critical illness.
Community-acquired cases present a diagnostic challenge because clinicians may not immediately think of acalculous cholecystitis when a patient walks in from the street with abdominal pain and no gallstones on imaging. The absence of stones can lead to false reassurance and delayed treatment, even as the gallbladder wall is deteriorating. Keeping the diagnosis in mind for patients with the right risk profile, even in the outpatient setting, is one of the clearest practical takeaways from the more recent literature on this condition.